[arch-general] FS#28008 - Bypass screensaver/locker program on xorg 1.11 and up

[Florian Pritz]

On 20.01.2012 18:38, Sébastien le Preste de Vauban wrote:
> El 20/01/12 04:10, Florian Pritz escribió:
>> On 20.01.2012 02:18, David J. Haines wrote:
>>> On Thu, Jan 19, 2012 at 8:08 PM, Tavian Barnes
>>> <tavianator at tavianator.com>  wrote:
>>>> On 19 January 2012 18:23, Dmitry Korzhevin<dkorzhevin at lsupport.net>  wrote:
>>>>> a funny bug in the Xorg server that could allow attackers with physical
>>>>> access to a machine to bypass the screensaver/screen locker program.
>>>>> Most people use those programs to lock their computer when they are
>>>>> away. On Gnome, gnome-screensaver is responsible for this. On KDE,
>>>>> kscreenlocker is. There is a wide variety of smaller tools doing the
>>>>> same thing, e.g. slock, slimlock, i3lock...
>>>>>
>>>>> Read more:
>>>>> http://gu1.aeroxteam.fr/2012/01/19/bypass-screensaver-locker-program-xorg-111-and-up
>>>>>
>>>>> ctrl+atl+*(on num lock keyboard) confirmed and work in arch linux.
>>>> IMO, it's not an X.Org or configuration bug, it's a bug in all the
>>>> screen lockers.
>>>>
>>>> http://seclists.org/oss-sec/2012/q1/217
>>>>
>>>> --
>>>> Tavian Barnes
>>> No Happy Hacking Keyboard (1996 IBM Model M, baby!), but I do use a
>>> custom keyboard layout that allows me to type international letters
>>> and switch entirely to a phonetic Cyrillic layout.
>> Please check if your custom layout contains the string "XF86_ClearGrab"
>> (maybe also without the underscore) and if yes, replace it with
>> "NoSymbol". Don't forget to reload it afterwards.
>>
> I did that and it solved the problem with the ctrl+atl+* key combo, but 
> I realized that ctrl+atl+/ does the same thing =(
> I attach my custom xkbcomp file.

The 4 debug symbols are: XF86LogGrabInfo, XF86Ungrab, XF86ClearGrab,
XF86LogWindowTree

Ungrab and ClearGrab can break things, while Log* are pretty harmless.

-- 
Florian Pritz

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